Claude + Lean formally verifies Agent SDK, yielding 16 bug-fix PRs from short prompts
JiaweiLiu_ · x · 2026-09-24
Anthropic engineer Boris Cherny shares that he used Opus 5.5 with Lean to formally verify the Claude Agent SDK — a couple of short prompts produced 16 PRs fixing bugs and race conditions. He sometimes combines Lean and TLA+ to hunt issues in data flow, concurrency, and state management, noting Claude excels at both despite his own unfamiliarity.
Related ecosystem work from the TLA+ community and Specula team:
- Specula: an agentic tool that models system code in TLA+ and uses model checkers to surface hundreds of deep bugs (480 stars on GitHub)
- TLAPS-Bench: a proof service for TLA+ specs; AI proved classic protocols like 2PC, Paxos, and TCP, forcing the team to retire all proof-completion tasks as too easy
- Proving low-level specs of real-world system code from scratch remains non-trivial
Related event: Opus 5.5 + Lean Formally Verifies Agent SDK, Yielding 16 Bug-Fix PRs(13 posts)→
More from coding & agent
- boat.dev agent sandboxes: Linux VMs from $0.018/hr with resize on resume — cem2ran · 2026-09-24
- Setting Astra's Thinking to 'Extra High' Makes It Over-Engineer Unit Tests — astralmatrix · 2026-09-24
- Free O'Reilly Book Offers a Pragmatic Framework for Scaling AI in Engineering Teams — blaizedsouza · 2026-09-24
- Zilliz CTO: agents make the enterprise data layer impossible to ignore — No_Engineer_1224 · 2026-09-24
- Running Android emulator + Chrome with 60fps streaming in a $0.072/hr cloud VM for always-on agents — cem2ran · 2026-09-24
- 10 agent reruns reached the right neighborhood, none reproduced the key observation — rohanpaul_ai · 2026-09-24